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Questions and Answers
What effect does ADH have on the collecting ducts during urine formation?
What effect does ADH have on the collecting ducts during urine formation?
The osmolarity of the medulla decreases during the formation of concentrated urine.
The osmolarity of the medulla decreases during the formation of concentrated urine.
False
What is the primary function of the vasa recta?
What is the primary function of the vasa recta?
To supply nutrients and oxygen to the nephron and maintain the osmolarity gradient in the medulla.
The bladder has a capacity averaging _____ mL.
The bladder has a capacity averaging _____ mL.
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Match the urine components with their abnormalities detected in routine urinalysis:
Match the urine components with their abnormalities detected in routine urinalysis:
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Which statement accurately describes the mechanism of urine transportation through the ureters?
Which statement accurately describes the mechanism of urine transportation through the ureters?
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The process of micturition is entirely involuntary.
The process of micturition is entirely involuntary.
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What triggers the spinal reflex responsible for micturition?
What triggers the spinal reflex responsible for micturition?
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What is the normal pH range of body fluids?
What is the normal pH range of body fluids?
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Metabolic acidosis can be caused by excessive vomiting.
Metabolic acidosis can be caused by excessive vomiting.
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What substance may combine with excess H+ in the kidney?
What substance may combine with excess H+ in the kidney?
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When urine concentration is low due to high fluid intake, the urine is _____ and of high volume.
When urine concentration is low due to high fluid intake, the urine is _____ and of high volume.
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Match the following urine characteristics with their corresponding fluid intake levels:
Match the following urine characteristics with their corresponding fluid intake levels:
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What is a potential effect of metabolic alkalosis?
What is a potential effect of metabolic alkalosis?
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What is the osmolarity of glomerular filtrate compared to blood?
What is the osmolarity of glomerular filtrate compared to blood?
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The thick ascending limb of the renal tubule has high water permeability.
The thick ascending limb of the renal tubule has high water permeability.
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What is the primary function of the nephron in the urinary system?
What is the primary function of the nephron in the urinary system?
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Polyuria is defined as the production of urine exceeding 1 liter per day.
Polyuria is defined as the production of urine exceeding 1 liter per day.
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What condition is characterized by the production of less than 400 mL of urine per day?
What condition is characterized by the production of less than 400 mL of urine per day?
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The process by which urine is expelled from the bladder is called __________.
The process by which urine is expelled from the bladder is called __________.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Which of the following is NOT a function of the urinary system?
Which of the following is NOT a function of the urinary system?
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The female urinary system has a longer urethra compared to the male urinary system.
The female urinary system has a longer urethra compared to the male urinary system.
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What are the four main parts of the urinary system?
What are the four main parts of the urinary system?
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Study Notes
The Urinary System
- Consists of: kidneys, ureters, bladder, and urethra.
- Controls volume and composition of body fluids.
- Average urine production is 1-2 liters per day.
- Variations in urine production can indicate medical issues.
- Polyuria: Excessive urine production (>2.5 L/day).
- Oliguria: Low urine production (<400 mL/day).
- Anuria: Very low urine production (< 100 mL/day).
Nephrons
- Basic functional unit of the kidney.
- Regulate water and soluble substances concentration in the blood.
Urination
- Ejection of urine from the bladder to the exterior of the body.
Functions of the Urinary System
- Removal of waste products (urea, uric acid).
- Regulation of electrolyte balance.
- Maintaining acid-base balance (pH of body fluids between 7.37 and 7.43).
Acid-Base Balance
- Kidney buffering capabilities: Excrete bicarbonate or form new bicarbonate and add it to the blood.
- Excess hydrogen (H+) may combine with phosphate ions, ammonia, or bicarbonate.
- H+ + ammonia => enters bloodstream
- H+ + phosphate => excreted in urine
Metabolic Acidosis
- Caused by severe diarrhea or kidney disease.
- Affects the central nervous system.
- Could lead to fatal coma.
Metabolic Alkalosis
- Caused by severe vomiting/dehydration, hormonal disorders, or overuse of antacids.
- Overstimulated nerves may result in muscle spasms or convulsions.
Urine Production
- Fluid intake is highly variable.
- Urine concentration varies with ADH (Antidiuretic Hormone).
- High fluid intake leads to dilute urine of high volume.
- Low fluid intake leads to concentrated urine of low volume.
Formation of Dilute Urine
- Glomerular filtrate and blood have the same osmolarity (300mOsm/Liter).
- Tubular osmolarity changes because of a concentration gradient in the medulla.
Tubule Osmolarity
- Descending limb: Osmolarity increases.
- Ascending limb: Osmolarity decreases.
- Collecting Duct: Osmolarity decreases further.
Thick Ascending Limb
- Actively resorbs Na+, K+, Cl– through symporters (carrier proteins).
- Low water permeability.
- Solutes leave, water stays in the tubule.
Collecting Duct
- Low water permeability in the absence of ADH.
Formation of Concentrated Urine
- Achieved by juxtamedullary nephrons with long loops.
- Osmotic gradient is created by the Countercurrent Multiplier.
- Solutes are pumped out of the ascending limb while water stays in the tubule.
- Medulla osmolarity is increased.
- In the presence of ADH, collecting ducts become very permeable to water, making the tubular fluid highly concentrated.
- The movement of water also carries urea into the medulla, further contributing to its osmolarity.
Countercurrent Exchange
- Loop and duct cells require nutrient and oxygen from blood supply.
- Capillaries feeding them (vasa recta) form loops like those of the nephron loops in the medulla.
- Incoming and outgoing blood will have similar osmolarity, maintaining the medulla concentration gradient.
Evaluation of Kidney Function
- Routine urinalysis assesses for abnormalities in the urine:
- Albumin
- Glucose
- Red blood cells
- Ketone bodies
- Microbes
Urine Transportation and Storage
- Each ureter transports urine from a renal pelvis by peristaltic waves, hydrostatic pressure, and gravity.
- There's no anatomical valve at the opening of the ureter into the bladder.
- When the bladder fills, it compresses the opening, preventing backflow.
- The bladder is a hollow, distensible, muscular organ with a capacity averaging 700–800 mL.
Micturition
- The discharge of urine involves voluntary and involuntary muscle contractions.
- Stretch receptors trigger a spinal reflex that we learn to control in childhood.
- The urethra carries urine from the internal urethral orifice to the exterior of the body.
- In males, it discharges semen as well as urine.
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Description
Test your knowledge of the urinary system, including its components, functions, and the significance of urine production rates. This quiz covers essential topics such as nephrons, urination, and acid-base balance.
